Open AccessTranscriptional Induction by Aromatic Amino Acids in Saccharomyces cerevisiae
Author(s) -
Ismaïl Iraqui,
Stéphan Vissers,
Brunó André,
Antonio Urrestarazu
Publication year - 1999
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.19.5.3360
Subject(s) - saccharomyces cerevisiae , biology , amino acid , biochemistry , yeast , genetics , microbiology and biotechnology
Aromatic aminotransferase II, product of theARO9 gene, catalyzes the first step of tryptophan, phenylalanine, and tyrosine catabolism inSaccharomyces cerevisiae. ARO9 expression is under the dual control of specific induction and nitrogen source regulation. We have here identified UASaro , a 36-bp upstream element necessary and sufficient to promote transcriptional induction of reporter gene expression in response to tryptophan, phenylalanine, or tyrosine. We then isolated mutants in which UASaro -mediatedARO9 transcription is partially or totally impaired. Mutations abolishingARO9 induction affect a gene calledARO80 (YDR421w ), coding for a Zn2 Cys6 family transcription factor. A sequence highly similar to UASaro was found upstream from theYDR380w gene encoding a homolog of bacterial indolepyruvate decarboxylase. In yeast, this enzyme is postulated to catalyze the second step of tryptophan catabolism to tryptophol. We show thatARO9 andYDR380w (namedARO10 ) have similar patterns of transcriptional regulation and are both under the positive control of Aro80p. Nitrogen regulation ofARO9 expression seems not directly to involve the general factor Ure2p, Gln3p, Nil1p, Uga43p, or Gzf3p.ARO9 expression appears, rather, to be mainly regulated by inducer exclusion. Finally, we show that Gap1p, the general amino acid permease, and Wap1p (Ycl025p), a newly discovered inducible amino acid permease with broad specificity, are the main aromatic amino acid transporters for catabolic purposes.